michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
michael@0:  * vim: set ts=8 sts=4 et sw=4 tw=99:
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /*
michael@0:  * JS atom table.
michael@0:  */
michael@0: 
michael@0: #include "jsatominlines.h"
michael@0: 
michael@0: #include "mozilla/ArrayUtils.h"
michael@0: #include "mozilla/RangedPtr.h"
michael@0: 
michael@0: #include <string.h>
michael@0: 
michael@0: #include "jscntxt.h"
michael@0: #include "jsstr.h"
michael@0: #include "jstypes.h"
michael@0: 
michael@0: #include "gc/Marking.h"
michael@0: #include "vm/Xdr.h"
michael@0: 
michael@0: #include "jscntxtinlines.h"
michael@0: #include "jscompartmentinlines.h"
michael@0: #include "jsobjinlines.h"
michael@0: 
michael@0: #include "vm/String-inl.h"
michael@0: 
michael@0: using namespace js;
michael@0: using namespace js::gc;
michael@0: 
michael@0: using mozilla::ArrayEnd;
michael@0: using mozilla::ArrayLength;
michael@0: using mozilla::RangedPtr;
michael@0: 
michael@0: const char *
michael@0: js::AtomToPrintableString(ExclusiveContext *cx, JSAtom *atom, JSAutoByteString *bytes)
michael@0: {
michael@0:     JSString *str = js_QuoteString(cx, atom, 0);
michael@0:     if (!str)
michael@0:         return nullptr;
michael@0:     return bytes->encodeLatin1(cx, str);
michael@0: }
michael@0: 
michael@0: const char * const js::TypeStrings[] = {
michael@0:     js_undefined_str,
michael@0:     js_object_str,
michael@0:     js_function_str,
michael@0:     js_string_str,
michael@0:     js_number_str,
michael@0:     js_boolean_str,
michael@0:     js_null_str,
michael@0: };
michael@0: 
michael@0: #define DEFINE_PROTO_STRING(name,code,init,clasp) const char js_##name##_str[] = #name;
michael@0: JS_FOR_EACH_PROTOTYPE(DEFINE_PROTO_STRING)
michael@0: #undef DEFINE_PROTO_STRING
michael@0: 
michael@0: #define CONST_CHAR_STR(idpart, id, text) const char js_##idpart##_str[] = text;
michael@0: FOR_EACH_COMMON_PROPERTYNAME(CONST_CHAR_STR)
michael@0: #undef CONST_CHAR_STR
michael@0: 
michael@0: /* Constant strings that are not atomized. */
michael@0: const char js_break_str[]           = "break";
michael@0: const char js_case_str[]            = "case";
michael@0: const char js_catch_str[]           = "catch";
michael@0: const char js_class_str[]           = "class";
michael@0: const char js_close_str[]           = "close";
michael@0: const char js_const_str[]           = "const";
michael@0: const char js_continue_str[]        = "continue";
michael@0: const char js_debugger_str[]        = "debugger";
michael@0: const char js_default_str[]         = "default";
michael@0: const char js_do_str[]              = "do";
michael@0: const char js_else_str[]            = "else";
michael@0: const char js_enum_str[]            = "enum";
michael@0: const char js_export_str[]          = "export";
michael@0: const char js_extends_str[]         = "extends";
michael@0: const char js_finally_str[]         = "finally";
michael@0: const char js_for_str[]             = "for";
michael@0: const char js_getter_str[]          = "getter";
michael@0: const char js_if_str[]              = "if";
michael@0: const char js_implements_str[]      = "implements";
michael@0: const char js_import_str[]          = "import";
michael@0: const char js_in_str[]              = "in";
michael@0: const char js_instanceof_str[]      = "instanceof";
michael@0: const char js_interface_str[]       = "interface";
michael@0: const char js_new_str[]             = "new";
michael@0: const char js_package_str[]         = "package";
michael@0: const char js_private_str[]         = "private";
michael@0: const char js_protected_str[]       = "protected";
michael@0: const char js_public_str[]          = "public";
michael@0: const char js_send_str[]            = "send";
michael@0: const char js_setter_str[]          = "setter";
michael@0: const char js_static_str[]          = "static";
michael@0: const char js_super_str[]           = "super";
michael@0: const char js_switch_str[]          = "switch";
michael@0: const char js_this_str[]            = "this";
michael@0: const char js_try_str[]             = "try";
michael@0: const char js_typeof_str[]          = "typeof";
michael@0: const char js_void_str[]            = "void";
michael@0: const char js_while_str[]           = "while";
michael@0: const char js_with_str[]            = "with";
michael@0: 
michael@0: // Use a low initial capacity for atom hash tables to avoid penalizing runtimes
michael@0: // which create a small number of atoms.
michael@0: static const uint32_t JS_STRING_HASH_COUNT = 64;
michael@0: 
michael@0: struct CommonNameInfo
michael@0: {
michael@0:     const char *str;
michael@0:     size_t length;
michael@0: };
michael@0: 
michael@0: bool
michael@0: JSRuntime::initializeAtoms(JSContext *cx)
michael@0: {
michael@0:     atoms_ = cx->new_<AtomSet>();
michael@0:     if (!atoms_ || !atoms_->init(JS_STRING_HASH_COUNT))
michael@0:         return false;
michael@0: 
michael@0:     if (parentRuntime) {
michael@0:         staticStrings = parentRuntime->staticStrings;
michael@0:         commonNames = parentRuntime->commonNames;
michael@0:         emptyString = parentRuntime->emptyString;
michael@0:         permanentAtoms = parentRuntime->permanentAtoms;
michael@0:         return true;
michael@0:     }
michael@0: 
michael@0:     permanentAtoms = cx->new_<AtomSet>();
michael@0:     if (!permanentAtoms || !permanentAtoms->init(JS_STRING_HASH_COUNT))
michael@0:         return false;
michael@0: 
michael@0:     staticStrings = cx->new_<StaticStrings>();
michael@0:     if (!staticStrings || !staticStrings->init(cx))
michael@0:         return false;
michael@0: 
michael@0:     static const CommonNameInfo cachedNames[] = {
michael@0: #define COMMON_NAME_INFO(idpart, id, text) { js_##idpart##_str, sizeof(text) - 1 },
michael@0:         FOR_EACH_COMMON_PROPERTYNAME(COMMON_NAME_INFO)
michael@0: #undef COMMON_NAME_INFO
michael@0: #define COMMON_NAME_INFO(name, code, init, clasp) { js_##name##_str, sizeof(#name) - 1 },
michael@0:         JS_FOR_EACH_PROTOTYPE(COMMON_NAME_INFO)
michael@0: #undef COMMON_NAME_INFO
michael@0:     };
michael@0: 
michael@0:     commonNames = cx->new_<JSAtomState>();
michael@0:     if (!commonNames)
michael@0:         return false;
michael@0: 
michael@0:     FixedHeapPtr<PropertyName> *names = reinterpret_cast<FixedHeapPtr<PropertyName> *>(commonNames);
michael@0:     for (size_t i = 0; i < ArrayLength(cachedNames); i++, names++) {
michael@0:         JSAtom *atom = Atomize(cx, cachedNames[i].str, cachedNames[i].length, InternAtom);
michael@0:         if (!atom)
michael@0:             return false;
michael@0:         names->init(atom->asPropertyName());
michael@0:     }
michael@0:     JS_ASSERT(uintptr_t(names) == uintptr_t(commonNames + 1));
michael@0: 
michael@0:     emptyString = commonNames->empty;
michael@0:     return true;
michael@0: }
michael@0: 
michael@0: void
michael@0: JSRuntime::finishAtoms()
michael@0: {
michael@0:     if (atoms_)
michael@0:         js_delete(atoms_);
michael@0: 
michael@0:     if (!parentRuntime) {
michael@0:         if (staticStrings)
michael@0:             js_delete(staticStrings);
michael@0: 
michael@0:         if (commonNames)
michael@0:             js_delete(commonNames);
michael@0: 
michael@0:         if (permanentAtoms)
michael@0:             js_delete(permanentAtoms);
michael@0:     }
michael@0: 
michael@0:     atoms_ = nullptr;
michael@0:     staticStrings = nullptr;
michael@0:     commonNames = nullptr;
michael@0:     permanentAtoms = nullptr;
michael@0:     emptyString = nullptr;
michael@0: }
michael@0: 
michael@0: void
michael@0: js::MarkAtoms(JSTracer *trc)
michael@0: {
michael@0:     JSRuntime *rt = trc->runtime();
michael@0:     for (AtomSet::Enum e(rt->atoms()); !e.empty(); e.popFront()) {
michael@0:         const AtomStateEntry &entry = e.front();
michael@0:         if (!entry.isTagged())
michael@0:             continue;
michael@0: 
michael@0:         JSAtom *atom = entry.asPtr();
michael@0:         bool tagged = entry.isTagged();
michael@0:         MarkStringRoot(trc, &atom, "interned_atom");
michael@0:         if (entry.asPtr() != atom)
michael@0:             e.rekeyFront(AtomHasher::Lookup(atom), AtomStateEntry(atom, tagged));
michael@0:     }
michael@0: }
michael@0: 
michael@0: void
michael@0: js::MarkPermanentAtoms(JSTracer *trc)
michael@0: {
michael@0:     JSRuntime *rt = trc->runtime();
michael@0: 
michael@0:     // Permanent atoms only need to be marked in the runtime which owns them.
michael@0:     if (rt->parentRuntime)
michael@0:         return;
michael@0: 
michael@0:     // Static strings are not included in the permanent atoms table.
michael@0:     if (rt->staticStrings)
michael@0:         rt->staticStrings->trace(trc);
michael@0: 
michael@0:     if (rt->permanentAtoms) {
michael@0:         for (AtomSet::Enum e(*rt->permanentAtoms); !e.empty(); e.popFront()) {
michael@0:             const AtomStateEntry &entry = e.front();
michael@0: 
michael@0:             JSAtom *atom = entry.asPtr();
michael@0:             MarkPermanentAtom(trc, atom, "permanent_table");
michael@0:         }
michael@0:     }
michael@0: }
michael@0: 
michael@0: void
michael@0: JSRuntime::sweepAtoms()
michael@0: {
michael@0:     if (!atoms_)
michael@0:         return;
michael@0: 
michael@0:     for (AtomSet::Enum e(*atoms_); !e.empty(); e.popFront()) {
michael@0:         AtomStateEntry entry = e.front();
michael@0:         JSAtom *atom = entry.asPtr();
michael@0:         bool isDying = IsStringAboutToBeFinalized(&atom);
michael@0: 
michael@0:         /* Pinned or interned key cannot be finalized. */
michael@0:         JS_ASSERT_IF(hasContexts() && entry.isTagged(), !isDying);
michael@0: 
michael@0:         if (isDying)
michael@0:             e.removeFront();
michael@0:     }
michael@0: }
michael@0: 
michael@0: bool
michael@0: JSRuntime::transformToPermanentAtoms()
michael@0: {
michael@0:     JS_ASSERT(!parentRuntime);
michael@0: 
michael@0:     // All static strings were created as permanent atoms, now move the contents
michael@0:     // of the atoms table into permanentAtoms and mark each as permanent.
michael@0: 
michael@0:     JS_ASSERT(permanentAtoms && permanentAtoms->empty());
michael@0: 
michael@0:     AtomSet *temp = atoms_;
michael@0:     atoms_ = permanentAtoms;
michael@0:     permanentAtoms = temp;
michael@0: 
michael@0:     for (AtomSet::Enum e(*permanentAtoms); !e.empty(); e.popFront()) {
michael@0:         AtomStateEntry entry = e.front();
michael@0:         JSAtom *atom = entry.asPtr();
michael@0:         atom->morphIntoPermanentAtom();
michael@0:     }
michael@0: 
michael@0:     return true;
michael@0: }
michael@0: 
michael@0: bool
michael@0: AtomIsInterned(JSContext *cx, JSAtom *atom)
michael@0: {
michael@0:     /* We treat static strings as interned because they're never collected. */
michael@0:     if (StaticStrings::isStatic(atom))
michael@0:         return true;
michael@0: 
michael@0:     AtomHasher::Lookup lookup(atom);
michael@0: 
michael@0:     /* Likewise, permanent strings are considered to be interned. */
michael@0:     AtomSet::Ptr p = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
michael@0:     if (p)
michael@0:         return true;
michael@0: 
michael@0:     AutoLockForExclusiveAccess lock(cx);
michael@0: 
michael@0:     p = cx->runtime()->atoms().lookup(lookup);
michael@0:     if (!p)
michael@0:         return false;
michael@0: 
michael@0:     return p->isTagged();
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * When the jschars reside in a freshly allocated buffer the memory can be used
michael@0:  * as a new JSAtom's storage without copying. The contract is that the caller no
michael@0:  * longer owns the memory and this method is responsible for freeing the memory.
michael@0:  */
michael@0: MOZ_ALWAYS_INLINE
michael@0: static JSAtom *
michael@0: AtomizeAndtake(ExclusiveContext *cx, jschar *tbchars, size_t length, InternBehavior ib)
michael@0: {
michael@0:     JS_ASSERT(tbchars[length] == 0);
michael@0: 
michael@0:     if (JSAtom *s = cx->staticStrings().lookup(tbchars, length)) {
michael@0:         js_free(tbchars);
michael@0:         return s;
michael@0:     }
michael@0: 
michael@0:     AtomHasher::Lookup lookup(tbchars, length);
michael@0: 
michael@0:     AtomSet::Ptr pp = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
michael@0:     if (pp) {
michael@0:         js_free(tbchars);
michael@0:         return pp->asPtr();
michael@0:     }
michael@0: 
michael@0:     AutoLockForExclusiveAccess lock(cx);
michael@0: 
michael@0:     /*
michael@0:      * If a GC occurs at js_NewStringCopy then |p| will still have the correct
michael@0:      * hash, allowing us to avoid rehashing it. Even though the hash is
michael@0:      * unchanged, we need to re-lookup the table position because a last-ditch
michael@0:      * GC will potentially free some table entries.
michael@0:      */
michael@0:     AtomSet& atoms = cx->atoms();
michael@0:     AtomSet::AddPtr p = atoms.lookupForAdd(lookup);
michael@0:     if (p) {
michael@0:         JSAtom *atom = p->asPtr();
michael@0:         p->setTagged(bool(ib));
michael@0:         js_free(tbchars);
michael@0:         return atom;
michael@0:     }
michael@0: 
michael@0:     AutoCompartment ac(cx, cx->atomsCompartment());
michael@0: 
michael@0:     JSFlatString *flat = js_NewString<NoGC>(cx, tbchars, length);
michael@0:     if (!flat) {
michael@0:         js_free(tbchars);
michael@0:         js_ReportOutOfMemory(cx);
michael@0:         return nullptr;
michael@0:     }
michael@0: 
michael@0:     JSAtom *atom = flat->morphAtomizedStringIntoAtom();
michael@0: 
michael@0:     if (!atoms.relookupOrAdd(p, lookup, AtomStateEntry(atom, bool(ib)))) {
michael@0:         js_ReportOutOfMemory(cx); /* SystemAllocPolicy does not report OOM. */
michael@0:         return nullptr;
michael@0:     }
michael@0: 
michael@0:     return atom;
michael@0: }
michael@0: 
michael@0: /* |tbchars| must not point into an inline or short string. */
michael@0: MOZ_ALWAYS_INLINE
michael@0: static JSAtom *
michael@0: AtomizeAndCopyChars(ExclusiveContext *cx, const jschar *tbchars, size_t length, InternBehavior ib)
michael@0: {
michael@0:     if (JSAtom *s = cx->staticStrings().lookup(tbchars, length))
michael@0:          return s;
michael@0: 
michael@0:     AtomHasher::Lookup lookup(tbchars, length);
michael@0: 
michael@0:     AtomSet::Ptr pp = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
michael@0:     if (pp)
michael@0:         return pp->asPtr();
michael@0: 
michael@0:     /*
michael@0:      * If a GC occurs at js_NewStringCopy then |p| will still have the correct
michael@0:      * hash, allowing us to avoid rehashing it. Even though the hash is
michael@0:      * unchanged, we need to re-lookup the table position because a last-ditch
michael@0:      * GC will potentially free some table entries.
michael@0:      */
michael@0: 
michael@0:     AutoLockForExclusiveAccess lock(cx);
michael@0: 
michael@0:     AtomSet& atoms = cx->atoms();
michael@0:     AtomSet::AddPtr p = atoms.lookupForAdd(lookup);
michael@0:     if (p) {
michael@0:         JSAtom *atom = p->asPtr();
michael@0:         p->setTagged(bool(ib));
michael@0:         return atom;
michael@0:     }
michael@0: 
michael@0:     AutoCompartment ac(cx, cx->atomsCompartment());
michael@0: 
michael@0:     JSFlatString *flat = js_NewStringCopyN<NoGC>(cx, tbchars, length);
michael@0:     if (!flat) {
michael@0:         js_ReportOutOfMemory(cx);
michael@0:         return nullptr;
michael@0:     }
michael@0: 
michael@0:     JSAtom *atom = flat->morphAtomizedStringIntoAtom();
michael@0: 
michael@0:     if (!atoms.relookupOrAdd(p, lookup, AtomStateEntry(atom, bool(ib)))) {
michael@0:         js_ReportOutOfMemory(cx); /* SystemAllocPolicy does not report OOM. */
michael@0:         return nullptr;
michael@0:     }
michael@0: 
michael@0:     return atom;
michael@0: }
michael@0: 
michael@0: JSAtom *
michael@0: js::AtomizeString(ExclusiveContext *cx, JSString *str,
michael@0:                   js::InternBehavior ib /* = js::DoNotInternAtom */)
michael@0: {
michael@0:     if (str->isAtom()) {
michael@0:         JSAtom &atom = str->asAtom();
michael@0:         /* N.B. static atoms are effectively always interned. */
michael@0:         if (ib != InternAtom || js::StaticStrings::isStatic(&atom))
michael@0:             return &atom;
michael@0: 
michael@0:         AtomHasher::Lookup lookup(&atom);
michael@0: 
michael@0:         /* Likewise, permanent atoms are always interned. */
michael@0:         AtomSet::Ptr p = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
michael@0:         if (p)
michael@0:             return &atom;
michael@0: 
michael@0:         AutoLockForExclusiveAccess lock(cx);
michael@0: 
michael@0:         p = cx->atoms().lookup(lookup);
michael@0:         JS_ASSERT(p); /* Non-static atom must exist in atom state set. */
michael@0:         JS_ASSERT(p->asPtr() == &atom);
michael@0:         JS_ASSERT(ib == InternAtom);
michael@0:         p->setTagged(bool(ib));
michael@0:         return &atom;
michael@0:     }
michael@0: 
michael@0:     const jschar *chars = str->getChars(cx);
michael@0:     if (!chars)
michael@0:         return nullptr;
michael@0: 
michael@0:     return AtomizeAndCopyChars(cx, chars, str->length(), ib);
michael@0: }
michael@0: 
michael@0: JSAtom *
michael@0: js::Atomize(ExclusiveContext *cx, const char *bytes, size_t length, InternBehavior ib)
michael@0: {
michael@0:     CHECK_REQUEST(cx);
michael@0: 
michael@0:     if (!JSString::validateLength(cx, length))
michael@0:         return nullptr;
michael@0: 
michael@0:     static const unsigned ATOMIZE_BUF_MAX = 32;
michael@0:     if (length < ATOMIZE_BUF_MAX) {
michael@0:         /*
michael@0:          * Avoiding the malloc in InflateString on shorter strings saves us
michael@0:          * over 20,000 malloc calls on mozilla browser startup. This compares to
michael@0:          * only 131 calls where the string is longer than a 31 char (net) buffer.
michael@0:          * The vast majority of atomized strings are already in the hashtable. So
michael@0:          * js::AtomizeString rarely has to copy the temp string we make.
michael@0:          */
michael@0:         jschar inflated[ATOMIZE_BUF_MAX];
michael@0:         InflateStringToBuffer(bytes, length, inflated);
michael@0:         return AtomizeAndCopyChars(cx, inflated, length, ib);
michael@0:     }
michael@0: 
michael@0:     jschar *tbcharsZ = InflateString(cx, bytes, &length);
michael@0:     if (!tbcharsZ)
michael@0:         return nullptr;
michael@0:     return AtomizeAndtake(cx, tbcharsZ, length, ib);
michael@0: }
michael@0: 
michael@0: JSAtom *
michael@0: js::AtomizeChars(ExclusiveContext *cx, const jschar *chars, size_t length, InternBehavior ib)
michael@0: {
michael@0:     CHECK_REQUEST(cx);
michael@0: 
michael@0:     if (!JSString::validateLength(cx, length))
michael@0:         return nullptr;
michael@0: 
michael@0:     return AtomizeAndCopyChars(cx, chars, length, ib);
michael@0: }
michael@0: 
michael@0: bool
michael@0: js::IndexToIdSlow(ExclusiveContext *cx, uint32_t index, MutableHandleId idp)
michael@0: {
michael@0:     JS_ASSERT(index > JSID_INT_MAX);
michael@0: 
michael@0:     jschar buf[UINT32_CHAR_BUFFER_LENGTH];
michael@0:     RangedPtr<jschar> end(ArrayEnd(buf), buf, ArrayEnd(buf));
michael@0:     RangedPtr<jschar> start = BackfillIndexInCharBuffer(index, end);
michael@0: 
michael@0:     JSAtom *atom = AtomizeChars(cx, start.get(), end - start);
michael@0:     if (!atom)
michael@0:         return false;
michael@0: 
michael@0:     idp.set(JSID_FROM_BITS((size_t)atom));
michael@0:     return true;
michael@0: }
michael@0: 
michael@0: template <AllowGC allowGC>
michael@0: static JSAtom *
michael@0: ToAtomSlow(ExclusiveContext *cx, typename MaybeRooted<Value, allowGC>::HandleType arg)
michael@0: {
michael@0:     JS_ASSERT(!arg.isString());
michael@0: 
michael@0:     Value v = arg;
michael@0:     if (!v.isPrimitive()) {
michael@0:         if (!cx->shouldBeJSContext() || !allowGC)
michael@0:             return nullptr;
michael@0:         RootedValue v2(cx, v);
michael@0:         if (!ToPrimitive(cx->asJSContext(), JSTYPE_STRING, &v2))
michael@0:             return nullptr;
michael@0:         v = v2;
michael@0:     }
michael@0: 
michael@0:     if (v.isString())
michael@0:         return AtomizeString(cx, v.toString());
michael@0:     if (v.isInt32())
michael@0:         return Int32ToAtom(cx, v.toInt32());
michael@0:     if (v.isDouble())
michael@0:         return NumberToAtom(cx, v.toDouble());
michael@0:     if (v.isBoolean())
michael@0:         return v.toBoolean() ? cx->names().true_ : cx->names().false_;
michael@0:     if (v.isNull())
michael@0:         return cx->names().null;
michael@0:     return cx->names().undefined;
michael@0: }
michael@0: 
michael@0: template <AllowGC allowGC>
michael@0: JSAtom *
michael@0: js::ToAtom(ExclusiveContext *cx, typename MaybeRooted<Value, allowGC>::HandleType v)
michael@0: {
michael@0:     if (!v.isString())
michael@0:         return ToAtomSlow<allowGC>(cx, v);
michael@0: 
michael@0:     JSString *str = v.toString();
michael@0:     if (str->isAtom())
michael@0:         return &str->asAtom();
michael@0: 
michael@0:     return AtomizeString(cx, str);
michael@0: }
michael@0: 
michael@0: template JSAtom *
michael@0: js::ToAtom<CanGC>(ExclusiveContext *cx, HandleValue v);
michael@0: 
michael@0: template JSAtom *
michael@0: js::ToAtom<NoGC>(ExclusiveContext *cx, Value v);
michael@0: 
michael@0: template<XDRMode mode>
michael@0: bool
michael@0: js::XDRAtom(XDRState<mode> *xdr, MutableHandleAtom atomp)
michael@0: {
michael@0:     if (mode == XDR_ENCODE) {
michael@0:         uint32_t nchars = atomp->length();
michael@0:         if (!xdr->codeUint32(&nchars))
michael@0:             return false;
michael@0: 
michael@0:         jschar *chars = const_cast<jschar *>(atomp->getChars(xdr->cx()));
michael@0:         if (!chars)
michael@0:             return false;
michael@0: 
michael@0:         return xdr->codeChars(chars, nchars);
michael@0:     }
michael@0: 
michael@0:     /* Avoid JSString allocation for already existing atoms. See bug 321985. */
michael@0:     uint32_t nchars;
michael@0:     if (!xdr->codeUint32(&nchars))
michael@0:         return false;
michael@0: 
michael@0:     JSContext *cx = xdr->cx();
michael@0:     JSAtom *atom;
michael@0: #if IS_LITTLE_ENDIAN
michael@0:     /* Directly access the little endian chars in the XDR buffer. */
michael@0:     const jschar *chars = reinterpret_cast<const jschar *>(xdr->buf.read(nchars * sizeof(jschar)));
michael@0:     atom = AtomizeChars(cx, chars, nchars);
michael@0: #else
michael@0:     /*
michael@0:      * We must copy chars to a temporary buffer to convert between little and
michael@0:      * big endian data.
michael@0:      */
michael@0:     jschar *chars;
michael@0:     jschar stackChars[256];
michael@0:     if (nchars <= ArrayLength(stackChars)) {
michael@0:         chars = stackChars;
michael@0:     } else {
michael@0:         /*
michael@0:          * This is very uncommon. Don't use the tempLifoAlloc arena for this as
michael@0:          * most allocations here will be bigger than tempLifoAlloc's default
michael@0:          * chunk size.
michael@0:          */
michael@0:         chars = cx->runtime()->pod_malloc<jschar>(nchars);
michael@0:         if (!chars)
michael@0:             return false;
michael@0:     }
michael@0: 
michael@0:     JS_ALWAYS_TRUE(xdr->codeChars(chars, nchars));
michael@0:     atom = AtomizeChars(cx, chars, nchars);
michael@0:     if (chars != stackChars)
michael@0:         js_free(chars);
michael@0: #endif /* !IS_LITTLE_ENDIAN */
michael@0: 
michael@0:     if (!atom)
michael@0:         return false;
michael@0:     atomp.set(atom);
michael@0:     return true;
michael@0: }
michael@0: 
michael@0: template bool
michael@0: js::XDRAtom(XDRState<XDR_ENCODE> *xdr, MutableHandleAtom atomp);
michael@0: 
michael@0: template bool
michael@0: js::XDRAtom(XDRState<XDR_DECODE> *xdr, MutableHandleAtom atomp);
michael@0: